1. Field of the Invention
This concerns apparatus to regulate valve train operation of an internal combustion engine of the type with more than one intake valves per cylinder whereby only one of the intake valves is activated during low speed/low load operation of the engine for better fuel economy and more complete combustion. During operation of the engine under higher speed and greater load conditions, both valves are activated for greater response and power.
2. Description of Related Art
The subject valve regulating apparatus controls the operation of the engine valve train to increase engine efficiency and flexibility. It is specifically directed to a multi-valve type engine with at least two intake valves per cylinder. The apparatus activates only one intake valve during idle and low speed operative conditions to improve fuel economy and promote complete combustion of fuel. However during higher speed, higher load engine operation when better breathing and resultantly more power is called for, both intake valves are activated.
The subject apparatus provides a rotatable shaft with internal eccentric portions so that in one angular position the shaft supports all the lash adjuster of the engine. In a second angular position 180 degrees from the first, the eccentrics allow one lash adjuster for each combustion chamber to move downward and withdraw the associated rocker arm from interaction with the camshaft. Incorporation of this mechanism in an engine is relatively simple and does not require expensive modifications to cylinder head design. The mechanism is also easy to assemble and calibrate. It is simple, extremely reliable, and relatively cheap.
Others have attempted to provide valve regulation by mechanisms. One previous attempt to provide a selective deactivation of support by a lash adjuster is disclosed in U.S. Pat. No. 4,546,734 to Kodama. Kodama utilizes a pivotal cam member actuated by a solenoid actuator to open a bleed valve formed in the bottom of the hydraulic lash adjuster. Bleeding the lash adjuster causes it to collapse and withdraw the rocker arm from interaction with the camshaft.
Several other patents disclose mechanisms to deactivate or modify valve operation. For example, the mechanism disclosed in U.S. Pat. No. 3,413,965 to Gavasso uses a first camshaft to conventionally operate the valves and adds a second camshaft to establish the position of a pivotal adjustment member which is positioned between the second camshaft and the rocker arm. Similar dual camshaft systems are disclosed in U.S. Pat. Nos. 4,638,773 and 4,724,822 in which addition hydraulic mechanisms are added. The mechanism disclosed in U.S. Pat. No. 4,475,489 to Honda uses first and second camshafts each of which engage the rocker arm. The non-overhead cam type engine disclosed in the U.S. Pat. No. 4,414,935 to Curtis uses a rotatable slotted sleeve as a selectively adjustable pivot for a valve rocker arm in addition to the usual lash adjuster.
It is also known to use selectively controlled hydraulically actuators or mechanisms to move a support for a rocker arm as seen in U.S. Pat. Nos. 4,167,931; 4,188,933; and 4,462,353.